Uniform circular motion question

A ball of mass m is attached by two strings to a vertical rod. as shown above. The entire system rotates at constant angular velocity about the axis of the rod.
a)Assuming ω is large enough to keep both strings taut, find the force each string exerts on the ball in terms of ω, m, g, R, and .
b)Find the minimum angular velocity, ωmin for which the lower string barely remains taut.